Important Note: I'm Aware HaloWars is finished and that this is 99% imposible to happen, yet I do this because I want to! =D Let me be happy!
The purpose of this thread is to give ideas on how to make the flood playable. This thread will contain information about buildings, units, leaders, upgrades and abilities that the Flood could have if it ever becomes playable. I have drawn some concept arts of the Flood Base and buildings, in the future maybe I will start drawing some units too. The concepts aren't a whole product of my imagination since I used some Halo Graphic Novel's references (I had to use a normal notebook to draw the pictures because I'm out of blank sheets =P)
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The Flood:
As its name suggests, the Flood attacks in endless waves, ruthlessly breaking up resistance with a sheer weight of numbers. Reports from the events on Installation 04 indicate that the Flood is able to use available technology, and even repair and utilize interstellar vehicles. The horrifying possibility that this abomination might escape into the universe at large must be prevented at all costs. The Flood's potential growth while its "food" exists could lead to the end of all intelligent life.
Flood Core:
The flood core is the equivalent of the UNSC Firebase and the Covenant Citadel. Just as the Firebase the Core has several slots, normal slots and defensive slots so the player can "build" flood structures.
Upgrades:
-You can research Stages in order to increase the tech level.
-it can be upgraded to bring up a couple more slots.
Something that I really like about the Flood is how careless they seem, for example they always crash any ship the have in their clutches, so the Flood Core would work the same way, a covenant dropship controlled by the Flood would come from orbit and crash on the ground to install a Flood Core just as the ship crashes flood spores start to come out and form a Flood fog nearby.
Remember those Flood doors from the level Cortana in Halo3? Well I used those doors to represent the slots on the Flood base.

This concept shows the covenant spirit after the crash.

And this concept shows the Core from the top and its slots.
Flood defensive buildings:
The Flood just as the UNSC and The Covenant have its own defensive structures and they can be upgradeable in order to make them more efficient.
The Default defensive structure for the Flood would be a Tentacle (like those seen in the level "The Covenant" in Halo3 after the Arbiter says "we trade one villain for another") This tentacle would be kinda weak.

The Default Flood tentacle
The Player can upgrade the tentacle into a stronger tentacle in order to make it Anti-Infantry. The tentacle itself becomes thicker and tougher.

A stronger anti-infantry tentacle
The player can also choose to upgrade the default tentacle into a Spiked Tentacle for Anti-Vehicle combat. The tentacle becomes thicker and spikes start to grow so it can impale enemy vehicles.

An Anti-vehicle Spiked tentacle
And the last upgrade would be the Anti-Air upgrade wich turns the tentacle into a spiked pad that shoots spikes (Just like the ranged form of the Flood pure form)

An Anti-Air Spiked pad
Flood Tech Tree (Originally posted by Rotaretilbo)
• Proto-Gravemind (C: 500; E: 0): Three building slots
• Gravemind (C: 1000; E: 0): Increases building slots to five, adds four turret slots, and produces one energy
• Super Gravemind (C: 1000; E: 0): Increases building slots to seven and increases energy output to two
• Stalker Form (C: 200; E: 1; P: 2):
• Transform (C: 250; E: 0): Pure Forms get special ability
• Regurgitate (C: 500; E: 1): Tank Forms spew Infection Forms when not in combat
• Defense Curl (C: 800; E: 2): Turret Forms stop firing and quadruple damage resistance when under intense fire
• Juggernaut (C: 1500; E: 2; P: 10):
• Behemoth (C: 600; E: 1): Increases Juggernaut health and damage
• Doubled Aggression (C: 900; E: 2): Juggernauts are built two at a time for the price of one
• Calcium Roots (C: 50; E: 0): Produces calcium
• Deep Calcium Roots (C: 225; E: 1): Doubles calcium output
• Genetic Catalogues (C: 250; E: 0): General upgrades
• Empty the Warrens (C: 800; E: 2): Increase population limit by ten
• Medium Turret (C: 400; E: 0): Upgrade Turrets to medium
• Large Turret (C: 800; E: 1): Upgrade Turrets to large
• Frantic Growth (C: 500; E: 1): Increases rate at which Infection Forms are produced
• Biomass (C: 0; E: 0): Increases damage resistance to all Flood units and structures
• More Tentacles (C: 700; E: 1): Increases Tentacle Attack to two
• Most Tentacles (C: 700; E: 2): Increases Tentacle Attack to three
• Telepathic Link (C: 700; E: 1): Increases range of Dominate Will
• Mind Control (C: 1000; E: 2): Dominate Will lasts until used again
• Spawning Pod (C: 75; E: 0): Automatically produces Infection Forms and upgrades Combat Forms and Carrier Forms
• Infection Form (C: 0; E: 0; P: 0): Squad of five Infection Forms that can infect units
• Overwhelm (C: 200; E: 0): Adds extra member to Infection Forms
• Spread Out (C: 700; E: 2): Infection Forms less likely to pop each other upon death
• Penetrator (C: 400; E: 1): Decreases time taken for Infection Forms to infect units
• Combat Form (C: 0; E: 0; P: *): Cannot be built, must be infected
• Lunge (C: 200; E: 0): Combat Forms get special ability
• Memory (C: 400; E: 1): Combat Forms use the weapons infected with (Combat Forms stay in vehicle when infected)
• Advance (C: 700; E: 2): Combat Forms advance slowly on targets while
firing before wildly charging for melee attacks
• Carrier Form (C: 0; E: 0; P: 1): Cannot be built, must be infected
• Unholy Charge (C: 200; E: 0): Increases Carrier Form speed
• Defiling Explosion (C: 400; E: 1): Increases Carrier Form splash damage
• Twins (C: 700; E: 2): Upgrades Carrier Forms special ability
Leaders:
I've thought about some leaders, these leaders are just for gameplay (skirmish and multiplayer reasons so they don't have to fully obey story and timeline canon).
-Gravemind:
Pretty much this is the first leader people think when talnking about the flood, just as the UNSC leaders the gravemind doesn't have a controllable unit.
Unlocks:
-->Flood Stalker Form:

The flood stalker form its faster tougher and stronger than any other flood form, it comes as individuals rather than squads. It's Y ability allows them to turn into Tank forms it takes a little while to mutate, the tank form its even tougher and even stronger than the stalker form but is a lot more slow, Tank forms can hold their own against infantry and vehicles. It's Y ability would be Spitting an Infection form squad once a stalker form turns into a Tank form it cannot be turned back.

Tank form
Powers:
--> Flood Dispersal pods:

The flood dispersal pods can be called by pressing UP on the D-pad and after selecting them you choose where you want them to drop, you can only drop them in places without fog, the dispersal pods releases 3 flood squads: An infected marine squad, An infected brute squad and A stalker form.
Upgrades:
It can upgrade stalker forms to make them tougher
-its last upgrade would be a faster mutation.
-It can upgrade tank forms to make them faster.
-It makes them able to cover their face to absorb a bit of damage.
-its final upgrade would be to spit two squads instead of one infection form squad.
-It can upgrade dispersal pods so they can damage the area they drop in.
-It can also upgrade to 5 squads (2 marine squads, 2 brute squads, 1 stalker).
-And finally to 7 squads (3 marine squads, 2 brute squads, 2 stalkers).
-Infected Covenant Ministry:
I took this idea from "The Last voyage of the infinite succor" from the HGN, basically a minor cruiser gets controlled by Flood and its ministry gets infected too.
Powers:
-->Flood transport: It works just as the UNSC Pelicans with a slight twist, once the spirit reaches the destination it crashes dealing damage to enemy units nearby and releasing the transported units in exchange the transported units would suffer 20% from the total max life in damage.
-->Berserk: Temporarily increases attack rate, attack damage and health of all Flood units in the area of effect.
-->Regenerate: Just like the heal power from the UNSC, this heals all flood units inside the Area of effect.
Upgrades:
-It can upgrade to transport 50% more flood units.
-The second upgrade would be to increase the damage the spirit does when it crashes.
-the last upgrade reduces the damage taken by the flood units that were transported.
-Upgrades the Regenerate power so it last longer.
-Upgrades the regenerate power so it regenerates faster.
-Upgrades the Berserk Power so it last longer.
-Upgrades the Berserk power so it affects a wider area.
-Corrupted Monitor:
I took this idea from the halo3 terminals in where a Forerunner IA (Mendicant Bias) got corrupted by gravemind, so I thought it would be a nice addition to the flood leaders.
This leader doesn't get any powers because this one does have a controllable unit in the form of a monitor. The monitor is pretty tough and it has laser attacks which can obliterate vehicles and aircraft. The monitor's Y ability is to blow enemy infantry out of the way and causes them minor damage.
Unlocks:
-->Flood Stalker Form:

The flood stalker form its faster tougher and stronger than any other flood form, it comes as individuals rather than squads it can be created in the Flood Factory. It's Y ability allows them to turn into Ranged forms it takes a little while to mutate, The Ranged forms cannot move but it can inflict heavy ranged damage, it is specially effective against aircraft the Y ability of the ranged form is to turn back to the Stalker form, which lets it move pretty quickly and makes it good for controlling different areas around the map.

Flood Ranged form
Upgrades:
These upgrades are available at the Flood evolution hall.
-It can upgrade stalker forms to make them tougher.
-its last upgrade would be a faster mutation.
-Ranged forms can be upgraded so they can shoot faster
-and its second upgrade would make them able to cover themselves and absorb heavy damage for a short amount of time, the ranged forms cover as soon as they get a strong hit.
-The first upgrade increases the damage of the monitor's Y ability.
-The second upgrade gives the monitor a couple of sentinels at his side to help him fight.
-The third upgrade makes the monitor an air unit.
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The Flood would be the perfect third race to play with in Halo Wars, I know its late because Halo Wars is finnished but it could be added later as a heavy DLC.
The Flood relies in mass production and mass damage its worst weakness is the fact that they don't have air units but they can dominate ground combat by infecting or dealing damage with dispersal pods, flood transport and things like that. Those are all my ideas (so far) on the flood, I hope you like them and show your support, and Thanks for reading!
"Join Your Voice With Mine And Sing Victory Everlasting!"
[url=http://www.halowars.com/forums/thread/462055.aspx]My Flood Suggestions thread[/url]